The present invention relates to a developing toner detecting device for an image recording apparatus for recording an image by a toner latent image.
Conventionally, in an image recording apparatus of this kind, a toner supplied by a developing portion constituted by an independent unit provided separately from a photo-sensitive material electrically charged by oscillated laser light or the like is made to adhere onto the photo-sensitive material so as to form a toner latent image thereon, and the thus formed toner latent image is transferred onto recording paper to thereby perform image recording thereon. In the developing portion, there is provided a developing toner detecting device such as a toner detecting sensor or the like. The developing toner detecting device detects the fact that the quantity of residual toner in the developing portion has reached a predetermined value, and after performing copying on a predetermined number of sheets after the above-mentioned detection of the predetermined residual toner quantity, the developing toner detecting device informs a user of the fact that toner of the developing portion has been used up to thereby request the user to stop image recording and replace a unit in the developing portion.
In the above-mentioned image recording apparatus, there is a problem in the following point. That is, image recording can be performed on a certain number of sheets even after the developing toner detecting device has detected the predetermined residual toner quantity as described above. However, since the quantity of consumption of the developing toner may largely vary in accordance with contents of a user's document which is to be subject to image recording, the developing toner detecting device stops the use of the above-mentioned toner when image recording has been made on a minimum predetermined number of sheets after detection of the predetermined residual toner quantity. Accordingly, in spite of the fact that toner still remains in the above-mentioned developing portion by a quantity enough to form toner latent images, it is required to replace the unit of the developing portion and toner is thus wastefully consumed.